feat: align docs with code, finish_place, registered status, UI filters, tests, CI

- Add PLAN.md and sync backend docs, .env.example, API doc (404 details)
- Document mock DB and PORT/API_PORT in docs/backend.md; README monorepo + frontend/.env.example
- Migration 002: finish_place column, status registered; mapper and mock DB updated
- Frontend: registered status, finishPlace, calendar year/month filters, pace sparkline
- Extract createApp for tests; supertest + tsx; GitHub Actions CI

Made-with: Cursor

frontend/src/lib/raceMetrics.ts

@@ -89,6 +89,10 @@ export function getRaceCountdownLabel(date: string, now: Date = new Date()): str
   return `через ${days} дней`;
 }
 
+export function isCloseDistance(left: number, right: number): boolean {
+  return Math.abs(left - right) < 0.05;
+}
+
 export function getPaceLabel(finishTime: string | null, distanceKm: number): string | null {
   const totalSeconds = parseFinishTimeToSeconds(finishTime);
   if (!totalSeconds || distanceKm <= 0) {
@@ -102,9 +106,23 @@ export function getPaceLabel(finishTime: string | null, distanceKm: number): str
   return `${String(paceMinutes).padStart(2, "0")}:${String(paceRemainder).padStart(2, "0")} /км`;
 }
 
+export function getRaceStatusClassName(status: Race["status"]): string {
+  const base = "race-card__status";
+  if (status === "completed") {
+    return `${base} ${base}--completed`;
+  }
+  if (status === "registered") {
+    return `${base} ${base}--registered`;
+  }
+  return `${base} ${base}--planned`;
+}
+
 export function getRaceStatusLabel(status: Race["status"]): string {
   if (status === "completed") {
     return "пробежал";
   }
+  if (status === "registered") {
+    return "зарегистрирован";
+  }
   return "планирую";
 }